The 8Li + 2H reaction studied in inverse kinematics at 3.15 MeV/nucleon using the REX-ISOLDE post-accelerator

The reaction 8Li + 2H has been studied in inverse kinematics at the incident energy of 3.15 MeV/nucleon, using the REX-ISOLDE post-accelerator. The reaction channels corresponding to (d,p), (d,d), and (d,t) reactions populating ground states and low-lying excited states in 7 -9Li have been identified and the related angular distributions extracted and compared with coupled-channels, distorted-wave Born approximation (DWBA), and coupled-reaction-channels calculations. For the inelastic and (d,t) channels we find that higher order effects are very important and hence one needs to go beyond the simple DWBA to extract reliable structure information from these processes.Ministerio de Ciencia e Innovación FPA2006-13807-C02-01 FPA2009-08848 FPA2009-07653 FPA2009-07387 FPA2010-17142Unión Europea RII3-EURONS 50606

Evidence of a new state in 11^{11}Be observed in the 11^{11}Li β\beta-decay

Coincidences between charged particles emitted in the $\beta$-decay of $^{11}$Li were observed using highly segmented detectors. The breakup channels involving three particles were studied in full kinematics allowing for the reconstruction of the excitation energy of the $^{11}$Be states participating in the decay. In particular, the contribution of a previously unobserved state at 16.3 MeV in $^{11}$Be has been identified selecting the $\alpha$ + $^7$He$\to\alpha$ + $^6$He+n channel. The angular correlations between the $\alpha$ particle and the center of mass of the $^6$He+n system favors spin and parity assignment of 3/2$^-$ for this state as well as for the previously known state at 18 MeV.Comment: 13 pages, 6 figure

Study of β-delayed charged particle emission of 11Li: Evidence of new decay channels

5 pags., 3 figs. -- 9th International Conference on Clustering Aspects of Nuclear Structure and Dynamics (CLUSTERS'07) 3–7 September 2007, Stratford upon Avon, UKThe break-up of the 18.2 MeV state in 11Be was studied in a 11Li β-decay experiment. We report here on the study of the dominating breakup channels involving na6He or 3n2α in the final state, with special emphasis dedicated in this contribution to the three-particle channel. The two emitted charged particles were detected in coincidence using a highly segmented experimental set-up. The observed experimental energy-vs-energy scatter plot indicates a sequential breakup where nuclei of mass 4, alpha particles, and mass 7, 7He, are involved. A Monte-Carlo simulation of the sequential channel, 11Be* → α + 7He → nα6He was performed and compared to the experimental data and to a simulation of the direct break-up of the 18.2 MeV state nα6He by phase space energy distribution. The energy-versus-energy plot are explained by the sequential simulation but not by the phase space simulation. © 2008 IOP Publishing Ltd

Study of beta-delayed 3-body and 5-body breakup channels observed in the decay of ^11Li

The beta-delayed charged particle emission from ^11Li has been studied with emphasis on the three-body n+alpha+^6He and five-body 2alpha+3n channels from the 10.59 and 18.15 MeV states in ^11Be. Monte Carlo simulations using an R-matrix formalism lead to the conclusion that the ^AHe resonance states play a significant role in the break-up of these states. The results exclude an earlier assumption of a phase-space description of the break-up process of the 18.15 MeV state. Evidence for extra sequential decay paths is found for both states.Comment: 16 pages, 9 figures. Submitted to Nuclear Physics

Coulomb breakup of 17 Ne from the view point of nuclear astrophysics

6 pags., 5 figs. -- XII International Symposium on Nuclei in the Cosmos, August 5-12, 2012, Cairns, AustraliaBy the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p, γ) 17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section σCoul has been determined, which then will be converted into a photo-absorption cross section σphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress.This project was supported by the German Federal Ministry for Education and Research (BMBF), EU(EURONS), EMMI-GSI, and HIC for FAI

Transfer reactions in inverse kinematics at REX-ISOLDE

Research on the structure of exotic nuclei is one of the most intriguing topics in present day nuclear physics. With the use of facilities for isotope separation on-line, such as ISOLDE at CERN, short-lived isotopes can be studied experimentally. Since 2002, the REX-ISOLDE facility enables radioactive ions produced by ISOLDE to be post-accelerated, increasing the energy of the ions enough to do nuclear transfer reactions in inverse kinematics. In this thesis, transfer reactions are used to study the structure of neutron-rich lithium isotopes through a series of experiments at REX-ISOLDE. The first experiment used a 9Li beam at 2.36 MeV/u impinging on a deuterated polyethylene target to study 10Li, 9Li and 8Li. For the (d,p)-channel the resonance ground state and a first excited state are observed and the results agree with theoretical calculations. The elastic channel agrees with Optical Model, OM, calculations. For the (d,t)-channel the shape of the angular distribution agrees with Distorted Wave Born Approximation, DWBA, calculations but the absolute scale is not reproduced. Therefore, a benchmark experiment with an 8Li beam at 3.15 MeV/u on the same target was made to test the validity of the method. Using OM calculations with the same potentials as for the 9Li experiment, the data from the elastic channel and OM agree on an absolute scale. The (d,p)-channel is well described for small scattering angles using DWBA calculations; the agreement extends to even larger angles if coupled-channels are taken into account. The conclusion is that transfer reactions remain a viable tool for investigating nuclear structure. Beyond the need to improve experimental obstacles such as increasing the beam energy, the analysis highlights the need of careful modelling of the reaction mechanism to be able to describe the data. The obtained results give confidence to investigate even more exotic nuclei and also to search for resonance states in unbound nuclei. The general analysis and simulation programs developed will be applicable for future experiments